1. Field of the Invention
The present invention relates to an aromatic heterocyclic compound, an organic light-emitting diode including the same, and a method of manufacturing the organic light-emitting diode, and more particularly, to an aromatic heterocyclic compound with excellent light-emitting characteristics, providing a low driving voltage, high efficiency, high brightness, high color purity and long life span when used in an organic light-emitting diode, and an organic light-emitting diode including an organic layer comprising the aromatic heterocyclic compound, and a method of manufacturing the organic light-emitting diode.
2. Description of the Related Art
Organic light-emitting diodes (OLED) are subject to intensive research due to their high brightness, low driving voltage, quick response time, and polychromatic characteristics.
Conventionally, OLEDs have a stacked structure of anode/organic emission layer/cathode, and may also have diverse structures such as anode/hole injection layer/hole transport layer/emission layer/electron transport layer/electron injection layer/cathode, and anode/hole injection layer/hole transport layer/emission layer/hole blocking layer/electron transport layer/electron injection layer/cathode.
Materials used for OLEDs may be classified into vacuum deposited materials and solution deposited materials, according to the method of manufacturing an organic layer of the OLEDs. The vacuum deposited materials should conventionally have a vapor pressure of 10−6 torr or higher, at 500° C. or less. In this regard, low-molecular weight materials with a mean molecular weight of 1200 or less are mainly used as vacuum deposited materials. The solution deposited material should have a high solubility to a solvent for forming a solution. The main types of solution deposited material include aromatic or heterocyclic compounds.
When OLEDs are manufactured using a vacuum deposition method, the usage of a vacuum system increases the manufacturing costs, and when a shadow mask is used in order to produce natural display pixels, it is difficult to produce high-resolution pixels. In contrast, solution deposition methods such as inkjet printing, screen-printing, and spin coating provide a convenient method of manufacturing an organic layer and at a low cost, and provide a higher resolution when compared to using a shadow mask.
However, conventional materials that are used for solution deposition are inferior in terms of thermostability and color purity, compared to the materials used for vacuum deposition. Moreover, even if the solution deposited materials have superior characteristics than the materials used for vacuum deposition, crystals of the deposited material are gradually formed after an organic layer is manufactured. The crystals have a size in the visible light wavelength range, scattering visible light and exhibiting white residues, and forming pin holes, and thus there is a strong likelihood of degradation of the OLED.
In Japanese Patent Laid-open Publication No. 1999-003782, an anthracene substituted with 2 naphthyl groups is disclosed as a compound that can be used for an emission layer. However, the compound has poor solubility for the solvent, and the characteristics of the OLED using the compound are not satisfactory.
Thus, development of a compound which can be used in an organic layer of an OLED so that the organic layer can have excellent thermostability and light-emitting characteristic regardless of the method of manufacturing the organic layer, is in demand.